PROBLEM: An implementation flaw allows unsigned Additional Decryption Keys (ADKs) to be added to a certificate and used for encryption. PLATFORM: Those running PGP versions 5.5.x through 6.5.3, both domestic and international. DAMAGE: The attacker who inserted the unsigned ADK can decrypt messages that were later encrypted using the altered certificate. SOLUTION: It is up to the sender to verify that the certificate that is used for encryption does not contain any unsigned ADKs. Network Associates, Inc. has released many product updates and HotFixes for this problem. Apply the appropriate update and/or HotFix.
VULNERABILITY The risk is MEDIUM. The vulnerability is difficult to exploit. ASSESSMENT:
[ Start Network Associates, Inc. Advisory ] PGP ADK Security Advisory On the morning of Thursday, August 24, researchers in Germany announced the discovery of a bug in PGP versions 5.5 through 6.5.3, regarding how those versions handle unauthorized Additional Decryption Key (ADK) additions to the unhashed/unsigned areas of PGP keys. This page provides the most up-to-date information regarding this issue and what steps Network Associates is taking. Please refer back to this page in the future for updates. As reported in the CERT advisory, exploitation of this bug is unlikely due to the unique circumstances under which an attack could be launched. To date, there have been no reported exploits. WHAT'S NEW Network Associates performed a thorough inspection of the world's largest public PGP keyserver (certserver.pgp.com), containing nearly 1.2 million PGP keys, and found that no keys contained on the server were affected by this issue. A software update has been applied to certserver.pgp.com and pgpkeys.mit.edu which automatically cleanses keys as they are uploaded to the servers. The cleansing process removes any signatures that have been tampered with (containing offending unhashed subpackets). A HotFix for PGP Certificate Server customers will be released soon that contains this update. Network Associates strongly recommends that customers download and install this HotFix on their PGP Certificate Servers as soon as it is available. We have released a new command line utility, PGPrepair 1.0, that will scan PGP keyrings and look for (and can repair) keys that have been tampered with. This utility is available on Windows, Solaris and Linux platforms. The PGPrepair tool is designed to repair keyrings created and/or used by PGP versions 2.6.2 and above. It can be applied to personal keyrings or to large keyserver keyrings (including PGP Certificate Servers). We have also released many product updates and HotFixes which resolve this issue. For more information about which versions of PGP are affected by this issue, what product updates/HotFixes are available and what we recommend you do regarding this issue, please visit the PGP Product Information Center for the ADK Security-Related Bug. Network Associates/PGP Security plans to release a detailed, formal advisory about this issue in the near future. (C) 2000, Network Associates, Inc. and its affiliated Companies. All Rights Reserved. [ End Network Associates, Inc. Advisory ]
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